Resin molded articles have been used as automobile components in recent years to reduce the weight of automobiles. Resins such as ABS resins, PC/ABS resins, PPE resins, and polyamide resins have been used to achieve this object, and such resin molded articles are often plated with copper, nickel, or the like to provide high quality impressions and beautiful appearance.
A common method for electroplating a resin molded article comprises degreasing and etching the molded article, optionally followed by neutralization and predipping, and then applying an electroless plating catalyst using a colloidal solution containing a tin compound and a palladium compound, optionally followed by activation (treatment with an accelerator), to perform electroless plating and electroplating sequentially.
In this case, for example, when an ABS resin is a substrate to be treated, a chromic acid mixture containing a mixed solution of chromium trioxide and sulfuric acid has been widely used as an etching solution. However, chromic acid mixtures, which contain toxic hexavalent chromium, adversely affect work environments. Moreover, safe disposal of the liquid waste requires reduction of the hexavalent chromium to a trivalent chromium ion, followed by neutralization and precipitation, thus requiring complicated treatment for the disposal of the liquid waste. Therefore, in consideration of workplace safety and adverse effects of the liquid waste on the environment, avoiding the use of chromic acid-containing etching solutions is preferable. However, highly safe etching solutions usable in place of chromic acid mixtures and capable of forming a plating film with a sufficient adhesion to various resin molded articles made of ABS resins or the like have yet to be developed.